std.heap.ArenaAllocator: fix incorrectly activating safety check
std.heap.ArenaAllocator: fix incorrectly activating safety check

raulgrell/zig,zig-lang/zig,andrewrk/zig,zig-lang/zig,raulgrell/zig,raulgrell/zig,Dimenus/zig,Dimenus/zig,zig-lang/zig,raulgrell/zig,andrewrk/zig,Dimenus/zig,raulgrell/zig